1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a semiconductor device having two transistors whose threshold voltages are equal to each other and to a semiconductor device.
2. Description of Related Art
In forming an amplification circuit by using transistors, it is necessary to use two transistors whose threshold voltages are equal to each other. For example, Patent Document (Japanese Patent Application Laid-Open No. 10-11975) describes a sense amplifier circuit in a semiconductor storage circuit. A flip-flop circuit is used as the sense amplifier circuit, and in the flip-flop circuit, two transistors whose threshold voltages are equal to each other are used.